1. This invention relates to chemistry and, more specifically, to novel compounds per se.
2. Description of the Prior Art
In various photographic systems for forming images, whether in black-and-white or in color, it is often desirable to include in the photographic film unit one or more of the various photographic reagents required for development and/or to enhance image quality. This practice extends to both conventional systems for forming negative images and to the various systems such as diffusion transfer, wherein a positive image in silver or in color is obtained.
In many instances, the photographic reagent may be contained initially in either the processing composition applied for development and image formation or in the film unit, the latter being preferred to reduce and hence simplify the number of ingredients required in the processing composition.
In other instances, the particular photographic reagent desired is not sufficiently stable in alkali to provide the requisite shelf life for the processing composition or the reagent is incompatible and/or reactable with another reagent of the composition and hence must be contained initially in the film unit.
In still other instances, the reagent must be provided at some particular time in the development process, which requires that it be contained in a specified layer or in specified proximity to another layer in the film unit.
In all of the foregoing instances it is desirable that the reagent be contained in the desired layer or layers of the particular film unit in such a manner that it is stable, non-migratory or non-diffusible, and yet available when required in the development process.
The art accordingly contains several references to "hydrolyzable" photographic reagent precursors. For example, U.S. Pat. No. 3,265,498 issued Aug. 9, 1966 discloses hydrolyzable development restrainer precursors, including those containing a mercapto-azole or mercapto-azine moiety. However, prior to the present invention, the novel quinone- and naphthoquinone-methide precursors of the present invention have been unknown in the art. Several commonly assigned copending applications and U.S. Patents disclose photographic uses for the class of novel quionone- or naphthoquinone methide hydrolyzable precursors of this invention. Copending application Ser. No. 349,063, filed Apr. 9, 1973 in the name of Stanley M. Bloom et al (and its parent application Ser. No. 210,650, filed Dec. 22, 1971 and now abandoned) describes a class of hydropyrimidine compounds within the scope of the present compounds as being useful development restrainers in dye developer diffusion transfer photographic color processes. U.S. Pat. No. 3,785,813, issued Jan. 15, 1974 from application Ser. No. 214,665, filed Jan. 3, 1972, discloses that species of the last-mentioned compounds wherein a ring system of one or more rings is fused to the hydropyrimidine nucleus exhibit sigificantly greater photographic activity, i.e., development restraint, in such diffusion transfer photographic color processes. Copending application Ser. No. 402,130, filed Oct. 1, 1973 as a continuation-in-part of the aforementioned application Ser. No. 214,665 claims the aforementioned polycyclic hydropyimidine compounds and precursors per se. U.S. Pat. No. 3,756,825, issued Sept. 4, discloses the use of said polycyclic hydropyimidine compounds as toners in black-and-white silver diffusion transfer processes. Our U.S. Pat. No. 3,674,478 issued July 4, 1972 describes integral positive-negative diffusion transfer products and processes employing novel compounds within the scope of this invention.